★英語聽力頻道為大家整理的初中英語聽力mp3：為什么有些人是雙關節(jié)，供大家參考。更多閱讀請查看本站英語聽力頻道。
Why Are Some People Double-Jointed? 為什么有些人是雙關節(jié)？
Can you bend your thumb backwards until it touches your wrist? If you join your hands behind your back, can you lift them over your head without letting go? 你是否能將大拇指向后彎曲直至其觸碰到手腕部位？你將雙手在背后緊握，是否能夠將其舉過頭頂而不松手？
If you can, you might be what some people call “double-jointed.” But, A Moment of Science wonders, how could anyone have double joints? 如果你能做到，那么你可能擁有雙關節(jié)。但是，《科學一刻》想知道，一個人怎么可能擁有雙關節(jié)呢？
Range Of Motion 活動范圍
Double-jointed people don’t really have two joints. Any joint, such as the thumb joint or the shoulder, can be called “double-jointed” if the tendons and ligaments surrounding the joint allow a wider range of motion than is usual. 所謂雙關節(jié)的人并非真正擁有兩個關節(jié)。任何關節(jié)，如肩關節(jié)或拇指關節(jié)，若圍繞其四周的韌帶和肌腱的活動范圍超出平常，則可被稱為“雙關節(jié)”。
Joints are created whenever 2 adjacent bones meet. They have fibrous bands of connective tissue called ligaments that stabilize the joint. Connective tissues also form the tendons that join the bones to the muscles. 關節(jié)是兩骨相接而形成的。他們含有被稱為韌帶的結締組織纖維帶，韌帶能夠穩(wěn)定關節(jié)。結締組織同時也組成了連接肌肉與骨頭的肌腱。
Ligaments and tendons usually restrict the movement of the joint, but in some people, these normally restrictive tissues can be quite flexible and allow the extra movement we call “double-jointed.” Practice can increase a joint’s natural flexibility just the way stretching can increase your muscles’ flexibility. 韌帶與肌腱通常會限制關節(jié)的活動，但是對于某些人來說，這些結締組織非常靈活，能做出更大范圍的運動，也就是我們所稱的“雙關節(jié)”。通過鍛煉能增加關節(jié)的自然柔韌性，正如伸展運動可加強肌肉的柔韌性一樣。
Flexibility 柔韌性
While flexible joints are very useful to contortionists, some joints can become so loose that they are unstable. This allows the bones of the joint to slip out of their sockets and can be very damaging. 靈活的關節(jié)對柔術演員來說至關重要，但他們的一些關節(jié)可能會變得十分不穩(wěn)固。這很容易造成關節(jié)脫臼，對身體造成很大的傷害。
Strengthening the muscles around the joint can stabilize it and still allow you to show off your trick joint at parties. 加強關節(jié)周圍肌肉的鍛煉能夠使關節(jié)穩(wěn)固，并且你依然可以在各式派對上炫耀你的小把戲。
Why Are Some People Double-Jointed? 為什么有些人是雙關節(jié)？
Can you bend your thumb backwards until it touches your wrist? If you join your hands behind your back, can you lift them over your head without letting go? 你是否能將大拇指向后彎曲直至其觸碰到手腕部位？你將雙手在背后緊握，是否能夠將其舉過頭頂而不松手？
If you can, you might be what some people call “double-jointed.” But, A Moment of Science wonders, how could anyone have double joints? 如果你能做到，那么你可能擁有雙關節(jié)。但是，《科學一刻》想知道，一個人怎么可能擁有雙關節(jié)呢？
Range Of Motion 活動范圍
Double-jointed people don’t really have two joints. Any joint, such as the thumb joint or the shoulder, can be called “double-jointed” if the tendons and ligaments surrounding the joint allow a wider range of motion than is usual. 所謂雙關節(jié)的人并非真正擁有兩個關節(jié)。任何關節(jié)，如肩關節(jié)或拇指關節(jié)，若圍繞其四周的韌帶和肌腱的活動范圍超出平常，則可被稱為“雙關節(jié)”。
Joints are created whenever 2 adjacent bones meet. They have fibrous bands of connective tissue called ligaments that stabilize the joint. Connective tissues also form the tendons that join the bones to the muscles. 關節(jié)是兩骨相接而形成的。他們含有被稱為韌帶的結締組織纖維帶，韌帶能夠穩(wěn)定關節(jié)。結締組織同時也組成了連接肌肉與骨頭的肌腱。
Ligaments and tendons usually restrict the movement of the joint, but in some people, these normally restrictive tissues can be quite flexible and allow the extra movement we call “double-jointed.” Practice can increase a joint’s natural flexibility just the way stretching can increase your muscles’ flexibility. 韌帶與肌腱通常會限制關節(jié)的活動，但是對于某些人來說，這些結締組織非常靈活，能做出更大范圍的運動，也就是我們所稱的“雙關節(jié)”。通過鍛煉能增加關節(jié)的自然柔韌性，正如伸展運動可加強肌肉的柔韌性一樣。
Flexibility 柔韌性
While flexible joints are very useful to contortionists, some joints can become so loose that they are unstable. This allows the bones of the joint to slip out of their sockets and can be very damaging. 靈活的關節(jié)對柔術演員來說至關重要，但他們的一些關節(jié)可能會變得十分不穩(wěn)固。這很容易造成關節(jié)脫臼，對身體造成很大的傷害。
Strengthening the muscles around the joint can stabilize it and still allow you to show off your trick joint at parties. 加強關節(jié)周圍肌肉的鍛煉能夠使關節(jié)穩(wěn)固，并且你依然可以在各式派對上炫耀你的小把戲。